I'm not trying to be a cynic. I should have clarified this issue. My suggestion is that rather than sending care packages and letters to random (anonymous) soldiers, go to your local church, American Legion, or VFW and find out who from your area is currently deployed. Then develop a relationship with those specific service members. That way you know where your tokens of regard are going, and you can have more certainty that they will be received and appreciated by an actual person. That way you will know what they actually want and need, instead of sending them stuff that they might be able to buy in the PX.
Believe me, your kindness will be cherished, and you might make a friendship that lasts a lifetime.